As part of the $630-million OC Bridges program, OCTA is building seven undercrossings or overcrossings to separate car traffic from rail traffic.

"This project translates into a better quality of life for residents and businesses in the area by speeding up commute times and eliminating the annoyance of having to wait at rail crossings for trains to pass by," said OCTA Chairman Shawn Nelson, also the county's Fourth District supervisor. "It's a great milestone to open this first grade-separation project to the public."

Work on the Placentia Avenue project, in the cities of Placentia and Fullerton, began in January 2012 and now, two lanes in each direction along Placentia Avenue are opened to the public. The contractor, Flatiron West, Inc., will continue working on finishing details to the project that are expected to be complete by June. OTCA says the undercrossing, when complete, is anticipated to cost about $69 million, a savings over the original $78 million estimate.

Work is continuing on the six other grade separations in the OC Bridges program, with the next milestone scheduled to be the opening of the Kraemer Avenue undercrossing later this year.